基于平行四边形机构的推力器推力测量研究

Study on thruster thrust measurement based on parallelogram mechanism

推力的精确测量在卫星姿态控制、引力波探测等领域均有重要应用,已经成为限制推力器技术发展的关键问题。国内外开展了很多推力测量相关的研究,但仍难以兼顾重负载和高精度。本文针对小推重比推力器推力测量困难的问题,提出了一种基于平行四边形机构的测量方法,并搭建了一套推力测量装置,其具有承载能力强、精度高、稳定性好的优点。其中平行四边形机构既作为推力器承载部件,又作为将推力转化为单自由度线性位移的弹性元件。微小位移由激光干涉仪测量,后基于胡克定律计算得到待测力值。设计了合理的机构参数,并对机构进行了力学仿真分析,理论承载能力达140kg。利用电磁力测试了装置的力学响应,实验结果表明,在2.5 kg的实际承重下,测量系统可分辨的最小力值为17.2μN,量程为17.2~2 789.9μN,相对不确定度为1.26%。该方法适用于推力器推力的测量,对推力器技术的发展具有重要意义。

The accurate thrust measurement has important application in the fields of satellite attitude control and gravitational wave detection, which has become a key issue limiting the development of thruster technology. Many related studies have been carried out at home and abroad. But, it is still difficult to balance heavy loads with high accuracy. In this article, we propose a measurement method based on parallelogram mechanism and build a thrust measurement device to address the problem of difficult thrust measurement of small thrust-to-weight ratio thrusters. It has advantages of high load carrying capacity, high accuracy and good stability. The parallelogram mechanism acts as both a thruster load-bearing component and an elastic element that converts the thrust into a single-degree-of-freedom linear displacement. The micro-displacement is measured by a laser interferometer. Then, the force value to be measured is calculated based on the Hooke′s law. The mechanical response of the device is tested by using electromagnetic force. Experimental results show that the minimum force value that can be resolved by the measurement system is 17.2 μN with a range of 17.2~2 789.9 μN and a relative uncertainty of 1.26% at an actual load-bearing capacity of 2.5 kg. The method is applicable to the measurement of thrust and is of great importance to the development of thruster technology.